Verizon's acquisition of AOL means that ads for some U.S. mobile users are about to get a whole lot more targeted.

The company has updated its privacy policy, saying that it now shares unique identifying information about users of its mobile phone network with the AOL Advertising Network, which claims as customers 74 of the top 100 websites tracked by ComScore.

The move will allow AOL to target ads at visitors to its sites and others using information from Verizon's databases as well as its own. According to Verizon's October 2015 privacy notice, the targeting criteria include visitors address, email address, age range, gender, interests, location, mobile web browsing history and app usage. The company can also track some non-mobile web browsing, to sites carrying AOL ads, it said.

Verizon links all this information together using a patchwork of identifiers, including ad IDs from Apple and Google, browser cookies from AOL, and its own Unique Identifier Header (UIDH) which it adds to mobile data traffic on its network. It's this last item that ads significantly to AOL's ad targeting power, as it's easy to delete or change the other identifiers.

Concern about targeted advertising is rising, with an increasing number of Internet users opting out of advertising altogether through the use of ad-blocking software. Apple recently made it possible to download content blockers for its Safari browser on iOS, prompting a flurry of players to enter the market.

Some see such blockers as a tool to force the online advertising industry to change its ways. One, Eyeo, deliberately lets through certain ads, as long as they are unobtrusive. It introduced has its own iOS content blocker -- but also taken steps to win over other developers to its platform by making its process for allowing some ads through the blocker more transparent.